Interrupter shield



June 29, 1954 s. c. KILLIAN INTERRUPTER SHIELD Filed May 24, 1952 JN ENTp Patented June 29, 1954 N TEED PATENT FilCE INTERRUPTER SHIELD Stanley G. Killian, ago, 111., assignor, by mesne assignments, to H. K. Porter Company, Inc.- .of Pittsburgh, Philadelphia, Pa, a corporation .of Pennsvlrania Application May 24, 1952, Serial No. 289,917

.7 Claims. (Cl. 200-148.)

The present inventionrelates to gas gblas t ,air

circuit interrupter switches and particularly: to

the arcs may be over :one hundred ieet in le gth. Various endeavors have been made to eliminate arcing, but none has been entirely successiul.

At the present time, air circuit interrupter switches are provided with a contact adapted. to be engaged by the switch blade, .a born .associated with the contact and adapted to be engaged ,by the switch blade upon opening and closing movement to prevent arcing at the contact and means tor directing a jBtsOl stream of .gas over the contact and horn to break any are that may occur. The provision .of a gas stream iorlquenching the arc has been very successful, but arcing still .may .occur to incorrect surfaces. thereby defeating the device. For example, the are .can move down the horn onto the contact lug or terminal pad, which is out of the gas stream. Also, ifa wind is blowing across phases, the arctends ,to lie in -.a somewhat horizontal plane entirely outside the ,gas stream. In addition to the foregoing, .it has been necessary-heretofore to locatethe gas nozzle in such position that .a part of the stream has been cut (Qfi by the contactin'sulator stack. This has been necessary in order .to reduce to .a minimum the possibility of amine in the two manners stated.

It is an object of the present invention to eliminate the possibility of arcing in switches of the character described by providing va shield ,for insulating all non-insulated parts of the switch that lie outside the gas stream.

Another Object of the present invention is to provide an economical insulating shield for interrupter switches thatmay .be .conveniently and rapidly associated with the switch to eliminate the possibility of arcing outside the gas stream.

A further object of the invention is the provision of a shield ,for interrupter switches that accommodates location of the gas nozzle in such position that the full stream of gas may be di- -rected in a wide path .over the contact and horn whereby a more efficient interrupter is provided. In other words, the shield of the present inven- 2 tion insulates all :parts .of the contact and horn mounting to eliminate arcing :in the two manners previously defined, so that the gas stream may be played on the contact and horn rather than having to be partially played upon the contact and horn mounting.

Other objects and advantages pf the present invention will become apparent the fQllowing detailed description of a preferred embodiment of th invention, wherein reference is made I to the accompanying drawings, in which:

Figure l is a side elevation of an .air circuit interrupter switch provided with the shield of the present invention Figure .2 is a partial side elevation of the contact and horn mounting With the shield of the present invention associated therewith;

Figure 3 is a rear 'view of the contact mounting and the shield, the view being taken substantially from the left hand side of Figure 2; and

Figure 4 ,is a top plan .view of the shield alone, the view showing the two parts of the shield disassembled.

The switch to which the shield of the present invention is applied is well (known in the art. However, reference being had to Figure 1, it is to be briefly pointed out that the switch comprise .a channel iron base frame I'll, that may be considered .as being disposed horizontally. The lease .or frame :10 carries three insulator stacks l2, M and 16, respectively, the middle one, M, of which carries means, indicated generally at It, for pivotally mounting a switch blade 20. The insulator stack 16 adjacent the switch blade stack 14 car ,ries a frame support .22 by means of which the switch blade 2-0 is connected in a high voltage circuit. The third insulator stack 12, at its upper end, carries a terminal :bracket 24 including a terminal pad .26 by means of which a contact .28 is connected in the circuit. The contact 28 is preferably U--shaped and adapted for the reception between the legs thereof of a reduced end portion 30 of the switch blade 2-0. A horn 32 is associated with the contact assembly and extends upwardly ,above the contact 28 for ena ement by the switch blade to prevent or re- .duce ancing at the contact.

Mounted on the frame 1.0 between the insulator stacks I2 and I4 :is .a nozzle 34 for projecting .a stream of gas against the contact and the horn. The nozzle 34 is mounted on a porcelain blast tube 36 which is supported .on the frame 19 by means of suitable br ckets. As ociated with the blast tube 36 is a cam and valve box 38 or opening and closing, movement of the switch blade.

In conventional structures, the nozzle 34 and the blast tube 36 are normally disposed substantially closer to the contact insulator stack I2 than is indicated in Figure 1 so that the entire stream of air is directed as much as possible against the entire upper end of the insulator stack l2. The object of such disposition of the nozzle 34 is to bathe the contact 28 and the horn 32 and as much as possible of the terminal bracket 24 with gas so as to prevent to the greatest extent possible arcing from the switch blade to the terminal bracket and pad. However, as will be apparent, the terminal pad 26 is disposed outside of the path of the gas stream since the same is shielded by the top fiange of the insulator stack. Accordingly, it has been possible heretofore for arcing to occurbetween the terminal pad and the the nozzle 34 and blast tube 36 are so disposed that the entire gas stream may be played in a wide path directly upon the contact 28 and the horn 32 so as to provide a highly efficient arc quenching function.

The insulating shield of the present invention is indicated generally at 40 and comprises a hollow" cap-like member adapted to be positioned over the terminal bracket 24and the terminal pad 26. The shield is provided in the top wall thereof with an aperture or passage 42 through which the contact 28 and the horn 32 are adapted to extend. The front face of the shield 40 is inclined to accommodate free flow of the gas stream to the contact 28 and the horn 32 and the inclined face also serves the purpose of guiding or directing the gas stream against the contact and the horn. As shown in the drawings, the shield preferably comprises a body portion 44 covering the terminal bracket 24 and fitting closely about the upper end of the insulator stack I2 and a reduced tail portion 46 extending over and covering the terminal pad 26. Since the body portion 44 projects downwardly over the top of the insulator stack I 2 and since the shield provides a complete covering for the terminal bracket and pad, insulation of the contact and horn mounting is insured.

The shield 40 may be formed in various manners and of various materials, but is preferably formed in two pieces or parts from porcelain. The shield is preferably split longitudinally into two halves which are substantially identical. At the forward end of the body portion 44, the two halves of the shield are provided with cooperating dove-tail portions 48 by mean of which the two halves may be connected together (see Figure 4) At the rearward edge of the body portion, each shield half is provided with a transverse wall 50 adapted to be secured to a bracket or plate to connect the two shield halves at the rearward end thereof. The transverse walls 50 of the shield halve are of a height extending from the bottom edge of the body portion 44 to the bottom edge of the tailportion 46 so as to accommodate passage of the terminal pad 26 over the top of the walls.

To mount the shield 40 on a switch, an L-shaped bracket 52 is mounted on the insulator stack I2. One-half of the shield is then placed on one side of the switch and the other half is then positioned on the other side of the switch but with the front portion thereof above the first half so that the cooperating dove-tail portions 48 may be engaged and the two halves of the shields slid into assembled relation, as is shown in Figures 1 to 3. Thereafter, the transverse wall portions 50 of the two halves may be secured to the vertical leg of the bracket 52, suitably by means of bolts 54,to secure the shield to the top of the insulator stack I2.

If desired, the shield 40 may be made in one piece, in which case the shield 40 is lowered over the horn 32 and the contact 28 and then is tilted to accommodate passage of the terminal pad 26 over the top of the wall portions 50 and into the tail portion 43 of the shield. The shield is then rocked forwardly to fit the body portion 44 thereof over the top of the insulator stack I2.

As will be appreciated, the shield is such as to prevent arcing from the switch blade to the terminal bracket and pad. Accordingly, the shield provide insulation for all non-insulated metallic portions of the blade and horn mounting atthe top of the insulator stack I2. The shield further accommodates the disposition of the contact 28 and the horn 32 directly in the gas stream and assists in directing the gas against the contact and the horn. Accordingly, the shield of the present invention will prevent arcing in paths lying outside of the gas stream. For this reason, the gas stream will be entirely eff cient in quenching arcing to provide a highly efficient interrupter switch. Likewise, the present invention accommodates the provision of a more effective and wider gas stream guided by the inclined front wall of the shield. The front wall of the shield is preferably disposed at a slight inclination to the center line of the gas stream or blast,but may be considered as being generally parallel to the center line of the nozzle or gas stream.

While I have described'what I regard to be a preferred embodiment of my invention, it will be appreciated that various changes, rearrangements and modifications may be made therein without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. A shield for air circuit interrupter switches having a contact insulator stack, a terminal bracket and pad carried thereby, and a contact carried by the bracket, said shield comprising a hollow cap-like member formed of insulating material, said member including a body portion adapted to be positioned over the top of the insulator stack, said body portion having an aperture in the top wall thereof for the passage of the contact, said body portion providing an insulated cover for the terminal'bracket, said member including a tail portion providing an insulated cover for the terminal pad, and means for securing said member to the insulator stack.

2. A shield for air circuit interrupter switches having a contact insulator stack, a terminal bracket and pad carried thereby, and a contact carried by the bracket, said shield comprising a hollow cap-like member formed of insulating material, said member including a, body portion adapted to be positioned over the top of the insulator stack, said body portion having an aperture in the top wall thereof for the passage of the contact, said body portion providing an insulated cover for the terminal bracket, said member including a tail portion providing an insulated cover for the terminal pad, and a bracket adapted to be secured to the stack, said body portion including wall means adjacent the stack adapted to be secured to said bracket.

3. A shield for air circuit interrupter switches having a contact insulator stack, a terminal bracket and pad carried thereby, and a contact carried by the bracket, said shield comprising a hollow cap-like member formed of insulating material, said member including a body portion adapted to be positioned over the top of the insulator stack, said body portion having an aperture in the top wall thereof for the passage of the contact, said body portion providing an insulated cover for the termina1 bracket, said member including a tail portion providing an insulated cover for the terminal pad, said member being split into two parts, said two parts having cooperating interengaging portions by means of which said two parts may be connected.

4. An air circuit interrupter switch comprising a pair of insulator stacks, a switch blade movably supported by one of said stacks, a terminal bracket and pad carried by the other of said stacks, a contact carried by said terminal bracket, said blade being adapted for movement toward and away from said contact, a horn associated with said contact in the path of movement of said blade, a nozzle directed toward said contact and said horn, a hollow cap-like insulating member positioned over said other stack, said member having an aperture therein through which said contact and said horn extend, said member providing an insulated cover for said terminal bracket and pad and the mounting of said horn, said member having an inclined face adjacent said nozzle, said face being disposed generally parallel to the axis of said nozzle.

5. An air circuit interrupter switch comprising a pair of insulator stacks, a switch blade movably supported by one of said stacks, a terminal bracket and pad carried by the other of said stacks, a contact carried by said termina1 bracket, said blade being adapted for movement toward and away from said contact, a horn associated with said contact in the path of movement of said blade, a nozzle directed toward said contact and said horn, and a hollow cap-like insulating member positioned over said other stack, said member comprising a body portion adapted to be positioned over the top of said other insulator stack, said body portion having an aperture in the top wall thereof through which said contact and said horn extend, said body portion providing an insulated cover for said terminal bracket, said member including a tail portion providing an insulated cover for the terminal pad, and means for securing said member to the insulator stack, said member having an inclined face adjacent said nozzle, said face being disposed to direct flow from said nozzle toward said contact and said horn.

6. An air circuit interrupter switch comprising a pair of insulator stacks, a switch blade movably supported by one of said stacks, a terminal bracket and pad carried by the other of said stacks, a contact carried by said terminal bracket, said blade being adapted for movement toward and away from said contact, a nozzle directed toward said contact, a hollow cap-like insulating member positioned over said other stack, said member including a body portion positioned over the top of the insulator stack, said body portion having an aperture in the top wall thereof through which said contact extends, said body portion providing an insulated cover for said terminal bracket, said body portion having an inclined front face adjacent said nozzle, said face being disposed at an inclination to the axis of said nozzle for directing flow from said nozzle towards said contact, said member including a tail portion providing an insulated cover for the terminal pad, said member being split longitudinally into two parts, the body portions of said two parts adjacent said inclined face having cooperating dove-tail portions by means of which said two parts may be connected, and a bracket secured to said other stack, said body portion including transverse wall means adjacent said stack but spaced from said inclined face, said transverse wall portions being secured to said bracket.

7. A shield for gas blast air circuit interrupter switches comprising a hollow cap of insulating material adapted to be positioned over the fixed switch contact mounting, said cap having an aperture in one wall thereof through which the fixed contact is adapted to extend outwardly of said cap, said cap further having an outside surface adapted to direct gas toward the outwardly extending portion of the contact.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 473,717 Varley, Jr Apr. 26, 1892 1,334,645 Bechoff et a1 Mar. 23, 1920 2,551,772 Thibaudat May 8, 1951 FOREIGN PATENTS Number Country Date 657,734 Germany Mar. 11, 1938 

